Abstract: Under the assumption that the durations of the available or disruption periods at the warehouse are mutually independent exponential distributions，firstly both the expected time length and cost of one cycle are developed for the warehouse’ stock.Secondly the long-run average cost model is established based on renewal reward theorems，so the optimal order quantity and optimal expected cost models are obtained.According to the analysis it is verified that the models are an extension of classic economic order quantity models and the optimal lot sizes are always less than the ones in a corresponding reliable case.Finally computational results show that the average operating cost of the unreliable warehouse is decreased significantly via effective inventory management，especially when the disruptions taken place at the warehouse are frequent.

Key words: inventory policy, supply chain disruption, order model, renewal reward

摘要： 在假设库房工作和中断的持续时间分别服从独立的指数分布条件下，首先，确定库房库存循环的期望时间和费用，然后，基于更新报酬定理，构建它的长程平均费用模型，进而得到库房的最优订货量和最优期望费用模型。通过分析证实，该模型是经典经济订货批量模型的扩展，且库房不可靠时的最优订货量总小于可靠时的经济订货批量。最后，仿真试验表明，对不可靠库房库存的有效管理，可以降低系统的平均费用，尤其是当库房发生中断比较频繁的情况。

关键词: 库存策略, 供应链中断, 订货模型, 更新报酬